page 8

1    1. The first and most general Observation
2is, That Electrical Bodies
3draw not unless they be warm'd;
4which Rule though I have now and
5then found to admit of an Exception,
6(whereof I elsewhere offer an account,)
7yet, as to the generality of
8common Electricks, it holds well enough
9to give much countenance to
10our Doctrine, which teaches the effects
11of Electrical Bodies to be perform'd
12by Corporeal Emanations.
13For 'tis known, that Heat, by agitating
14the parts of a fit Body, solicites
15it as it were to send forth its Effluvia ,
16as is obvious in odoriferous Gums
17and Perfumes, which, being heated,
18send forth their fragrant steams, both
19further and more copiously than otherwise
20they would.
21    2. Next, it has been observ'd, that
22Amber, &c. warm'd by the fire, does
23not attract so vigorously, as if it acquire
24an equal degree of heat by
25being chaf'd or rub'd: So that the
26modification of motion in the internal
27parts, and in the Emanations of

page 9

28the Amber, may, as well as the degree
29of it, contribute to the Attraction.
30And my particular Observations
31incline me to adde, that the effect
32may oftentimes be much promoted,
33by employing both these
34ways successively; as I thought I manifestly
35found when I first warm'd
36the Amber at the fire, and presently
37after chaf'd it a little upon a piece
38of cloth. For then a very few rubbings
39seem'd to excite it more than
40many more would otherwise have
41done: As if the heat of the fire
42had put the parts into a general, but
43confus'd, agitation; to which 'twas
44easie for the subsequent Attrition
45(or Reciprocation of Pressure) to
46give a convenient modification in a
47Body whose Texture disposes it to
48become vigorously Electrical.
49    3. Another Observation that is
50made about these Bodies, is, That
51they require Tersion as well as Attrition;
52and though I doubt whether
53the Rule be infallible, yet I deny
54not but that weaker Electricks require

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55to be as well wip'd as chaf'd;
56and even good ones will have their
57Operation promoted by the same
58means. And this is very agreeable
59to our Doctrine, since Tersion, besides
60that it is, as I have sometimes
61manifestly known it, a kind or degree
62of Attrition, frees the Surface
63from those adherences that might
64choak the pores of the Amber, or
65at least hinder the emanation of the
66steams to be so free and copious as otherwise
67it would be.
68    4. 'Tis likewise observ'd, That
69whereas the Magnetical Steams are
70so subtile, that they penetrate and
71perform their Operation through
72all kind of Mediums hitherto known
73to us; Electrical Steams are like
74those of some odoriferous Bodies,
75easily check'd in their progress, since
76'tis affirm'd by Learned Writers, who
77say they speak upon particular Trial,
78that the interposition of the finest
79Linnen or Sarsnet is sufficient to hinder
80all the Operation of excited
81Amber upon a Straw or Feather

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82plac'd never so little beyond it.
83    5. It has been also observed, that
84the effects of Electrical Attraction
85are weaken'd if the air be thick and
86cloudy; and especially if the Southwind
87blows: And that Electricks display
88their vertue more faintly by
89night than by day, and more vigorously
90in clear weather, and when
91the winds are Northerly. All which
92the Learned Kircherus asserts himself
93to have found true by experience;
94insomuch that those bodies that are
95but faintly drawn when the weather
96is clear, will not, when 'tis thick
97and cloudy, be at all moved.
98    6. We have also observed, That
99divers Concretes, that are notably
100Electrical, do abound in an effluviable
101matter (if I may so call it)
102which is capable of being manifestly
103evaporated by heat and rubbing.
104Thus we see, that most Resinous
105Gums, that draw light bodies, do
106also, being moderately solicited by
107heat, (whether this be excited by
108the fire, or by Attrition or Contusion)

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109emit steams. And in pieces of
110Sulphur conveniently shaped, I found
111upon due Attrition a Sulphureous
112stink. And that piece of Amber
113which I most employ, being somewhat
114large and very well polish'd,
115will, being rub'd upon a piece of
116woollen cloth, emit steams, which
117the nostrils themselves may perceive;
118and they sometimes seem to
119me not unlike those that I took notice
120of, when I kept in my mouth a
121drop or two of the diluted Tincture
122(or Solution of the finer parts) of
123Amber made with Spirit of Wine,
124or of Sal Armoniac.
125    7. It agrees very well with what
126has been said of the corporeal Emanations
127of Amber, that its attractive
128power will continue some time after
129it has been once excited. For the
130Attrition having caus'd an intestine
131commotion in the parts of the Concrete,
132the heat or warmth that is
133thereby excited ought not to cease,
134as soon as ever the rubbing is over,
135but to continue capable of emitting

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136Effluvia for some time afterwards,
137which will be longer or shorter according
138to the goodness of the Electric,
139and the degree of the Antecedent
140commotion: which joyn'd
141together may sometimes make the
142effect considerable, insomuch that
143in a warm day, about noon, I did
144with a certain body, not much, if at
145all, bigger than a Pea, but very vigorously
146attractive, move to and fro
147a Steel Needle freely poysed, about
148three minutes (or the twentieth
149part of an hour) after I had left off
150rubbing the Attrahent.
151    8. That it may not seem impossible,
152that Electrical Effluvia should be
153able to insinuate themselves into the
154pores of many other bodies, I shall
155adde, that I found them subtile enough
156to attract not onely Spirit of
157Wine, but that the fluid aggregate of
158Corpuscles we call Smoak. For having
159well lighted a Wax-taper, which
160I preferr'd to a common Candle to
161avoid the stink of the snuff, I blew
162out the flame; and, when the smoak

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163ascended in a slender stream, held, at
164a convenient distance from it, an excited
165piece of Amber or a chafed
166Diamond, which would manifestly
167make the ascending smoak deviate
168from its former line, and turn aside,
169to beat, as it were, against the
170Electric, which, if it were vigorous,
171would act at a considerable distance,
172and seemed to smoak for a pretty
173while together.
174    9. That 'tis not in any peculiar
175Sympathy between an Electric and
176a body whereon it operates, that Electrical
177Attraction depends, seems
178the more probable, because Amber,
179for instance, does not attract onely
180one determinate sort of bodies, as
181the Loadstone does Iron, and those
182bodies wherein it abounds; but as far
183as I have yet tried, it draws indifferently
184all bodies whatsoever, being
185plac'd within a due distance from it,
186(as my choicest piece of Amber
187draws not onely Sand and Mineral
188Powders, but Filings of Steel and
189Copper, and beaten Gold it self)

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190provided they be minute or light enough,
191except perhaps it be fire:
192I employ the word perhaps , because
193I am not yet so clear in this point.
194For having applied a strong Electric
195at a convenient distance to small
196fragments of ignited matter, they
197were readily enough attracted, and
198shin'd, whilst they were sticking to
199the body that had drawn them: But
200when I look'd attentively upon
201them, I found the shining sparks to
202be, as it were, cloath'd with light
203ashes, which, in spite of my diligence,
204had been already form'd about
205the attracted Corpuscles, upon
206the expiring of a good part of the
207fire; so that it remain'd somewhat
208doubtful to me, whether the ignited
209Corpuscles, whilst they were totally
210such, were attracted; or whether
211the immediate objects of the
212Attraction were not the new form'd
213ashes, which carried up with them
214those yet unextinguished parts of
215fire, that chanc'd to be lodg'd in them.
216But, as for flame, our Countreyman

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217Gilbert delivers as his Experiment,
218That an Electric though duly excited
219and applied, will not move the
220flame of the slenderest Candle.
221Which some will think not so easie
222to be well tried with common Electricks,
223as Amber, hard Wax, Sulphur,
224and the like unctuous Concretes,
225that very easily take fire:
226Therefore I chose to make my Trial,
227with a rough Diamond extraordinarily
228attractive, which I could,
229without injuring it, hold as near as
230I pleas'd to the flame of a Candle or
231Taper; and though I was not satisfi'd
232that it did either attract the flame,
233as it visibly did the smoak, or manifestly
234agitate it; yet granting that
235Gilbert's Assertion will constantly
236hold true, and so, that flame is to be
237excepted from the general Rule, yet
238this exception may well comport
239with the Hypothesis hitherto countenanc'd,
240since it may be said, as 'tis,
241if I mistake not, by Kirkerus , that
242the heat of the flame dissipates the
243Effluvia , by whose means the Attraction

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244should be perform'd. To
245which I shall adde, that possibly the
246Celerity of the motion of the Flame
247upwards, may render it very difficult
248for the Electrical Emanations
249to divert the Flame from its Course.
250    10. We have found by Experiment,
251That a vigorous and well excited
252piece of Amber will draw, not
253onely the powder of Amber, but
254less minute fragments of it. And as
255in many cases one contrary directs to
256another, so this Trial suggested a
257further, which, in case of good success,
258would probably argue, that in
259Electrical Attraction not onely Effluvia
260are emitted by the Electrical body,
261but these Effluvia fasten upon
262the body to be drawn, and that in
263such a way, that the intervening viscous
264strings, which may be supposed
265to be made up of those cohering Effluvia ,
266are, when their agitation ceases,
267contracted or made to shrink inwards
268towards both ends, almost as a
269highly strech'd Lute-string does
270when 'tis permitted to retreat into

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271shorter Dimensions. But the Conjecture
272it self was much more easie
273to be made than the Experiment requisite
274to examine it. For we found
275it no easie matter to suspend an Electric,
276great and vigorous enough, in
277such a manner, that it might, whilst
278suspended, be excited, and be so
279nicely poised, that so faint a force as
280that wherewith it attracts light bodies
281should be able to procure a Local
282Motion to the whole Body it self.
283But after some fruitless attempts
284with other Electricks, I had recourse
285to the very vigorous piece of polish'd
286Amber, formerly mention'd,
287and when we had with the help of a
288little Wax suspended it by a silken
289thread, we chafed very well one of
290the blunt edges of it upon a kind of
291large Pin-cushion cover'd with a
292course and black woollen stuff, and
293then brought the Electric, as soon as
294we could, to settle notwithstanding
295its hanging freely at the bottom of
296the string. This course of rubbing
297on the edge of the Amber we pitch'd

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298upon for more than one reason; for
299if we had chafed the flat side, the
300Amber could not have approached
301the body it had been rub'd on without
302making a change of place in the
303whole Electric, and, which is worse,
304without making it move (contrary
305to the nature of heavy bodies)
306somewhat upwards; whereas the
307Amber having, by reason of its suspension,
308its parts counterpoised by
309one another; to make the excited
310edge approach to another body, that
311edge needed not at all ascend, but
312onely be moved horizontally, to
313which way of moving the gravity of
314the Electric (which the string kept
315from moving downwards) could be
316but little or no hinderance. And agreeably
317to this we found, that if, as
318soon as the suspended and well
319rubb'd Electric was brought to settle
320freely, we applied to the chafed
321edge, but without touching it, the
322lately mention'd Cushion, which, by
323reason of its rough Superficies and
324porosity, was fit for the Electrical

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325Effluvia to fasten upon, the edge
326would manifestly be drawn aside by
327the Cushion steadily held, and if
328this were slowly removed, would
329follow it a good way; and when
330this body no longer detain'd it,
331would return to the posture wherein
332it had settled before. And this power
333of approaching the Cushion by
334vertue of the operation of its own
335steams, was so durable in our vigorous
336piece of Amber, that by once
337chafing it, I was able to make it follow
338the Cushion no less than ten or
339eleven times. Whether from such
340Experiments one may argue, that 'tis
341but, as 'twere, by accident that Amber
342attracts another body, and not
343this the Amber; and whether these
344ought to make us question, if Electricks
345may with so much propriety,
346as has been hitherto generally supposed,
347be said to Attract , are doubts
348that my Design does not here oblige
349me to examine.
350    Some otherPhaenomena might be
351added of the same Tendency with

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352those already mention'd, (as the advantage
353that Electrical Bodies usually
354get by having well polish'd or at
355least smooth Surfaces,) but the Title
356of this Paper promising some Experiments
357about the Production of Electricity,
358I must not omit to recite,
359how I have been sometimes able to
360produce or destroy this Quality in
361certain bodies, by means of alterations,
362that appear'd not to be other
363than Mechanical.
364
365

EXPER. I.

366
367    And first, having with a very mild
368heat slowly evaporated about a
369fourth part of good Turpentine, I
370found, that the remaining body
371would not, when cold, continue a Liquor,
372but harden'd into a transparent
373Gum almost like Amber, which,
374as I look'd for, proved Electrical.
375

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376

EXPER. II.

377
378    Secondly, by mixing two such liquid
379Bodies as Petroleum and
380strong Spirit of Nitre in a certain
381proportion, and then distilling them
382till there remained a dry mass, I obtain'd
383a brittle substance as black as
384Jet; and whose Superficies (where
385it was contiguous to the Retort) was
386glossie like that Mineral when polished;
387and as I expected I found it
388also to resemble Jet, in being endowed
389with an Electrical Faculty.
390
391

EXPER. III.

392
393    Thirdly, Having burnt Antimony
394to ashes, and of those ashes,
395without any addition, made a transparent
396Glass, I found, that, when
397rubb'd, as Electrical Bodies ought to
398be to excite them, it answer'd my expectation,
399by manifesting a not inconsiderable
400Electricity. And this is the
401worthier of notice, because, that as a

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402Vitrum Antimonii , that is said to be
403purer than ordinary, may be made
404of the Regulus of the same Mineral,
405in whose preparation you know a
406great part of the Antimonial Sulphur
407is separated and left among the
408Scoriae ; so Glass of Antimony made
409without additament, may easily, as
410experience has inform'd us, be in
411part reduced to a Regulus , (a Body
412not reckon'd amongst Electrical
413ones.) And that you may not think,
414that 'tis onely some peculiar and fixt
415part of the Antimony that is capable
416of Vitrification , let me assure you,
417that even with the other part that is
418wont to flye away, (namely the
419Flowers) an Antimonial Glass may
420without an addition of other Ingredients
421be made.
422
423

EXPER. IV.

424
425    Fourthly, The mention of a Vitrified
426Body brings into my
427mind, that I more than once made
428some Glass of Lead per se , (which

page 24

429I found not very easie work) that
430also was not wholly destitute of an
431Electrical Vertue, though it had but
432a very languid one. And it is not
433here to be overlook'd, that this Glass
434might easily be brought to afford again
435malleable Lead, which was never
436reckon'd, that I know of, among
437Electrical Bodies.
438
439

EXPER. V.

440
441    Fifthly, Having taken some Amber,
442and warily distill'd it, not
443with Sand, or powder'd Brick, or
444some such additament as Chymists
445are wont to use, for fear it should
446boyl over or break their Vessels; but
447by it self, that I might have an unmixed
448Caput mortuum ; Having made
449this Distillation, I say, and continued
450it till it had afforded a good proportion
451of phlegm, Spirit, Volatile Salt,
452and Oyl, the Retort was warily broken,
453and the remaining matter was
454taken out in a lump, which, though
455it had quite lost its colour being

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456burnt quite black, and though it
457were grown strangely brittle in comparison
458of Amber, so that they who
459believe the vertue of attracting light
460Bodies to flow from the substantial
461form of Amber, would not expect
462it in a Body so changed and deprived
463of its noblest parts: Yet this Caput
464mortuum was so far from having lost
465its Electrical Faculty, that it seemed
466to attract more vigorously than Amber
467it self is wont to do before it be
468committed to Distillation.
469    And from the foregoing Instances
470afforded us by the Glass of Antimony,
471we may learn, that when the
472form of a Body seems to be destroyed
473by a fiery Analysis that dissipates
474the parts of it, the remaining substance
475may yet be endowed with Electricity,
476as the Caput mortuum of
477Amber may acquire it; as in the case
478of the Glass of Antimony made of
479the Calx and of the Flowers. And
480from the second Example abovementioned,
481and from common Glass
482which is Electrical, we may also

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483learn, that Bodies that are neither of
484them apart observed to be endowed
485with Electricity, may have that Vertue
486result in the compounded substance
487that they constitute, though
488it be but a factitious Body.
489    To the foregoing Experiments,
490whose success is wont to be uniform
491enough, I shall adde the Recital of a
492surprising Phaenomenon , which, though
493not constant, may help to make it
494probable, that Electrical Attractions
495need not be suppos'd still to proceed
496from the substantial, or even
497from the essential Form of the Attrahent;
498but may be the effects of
499unheeded, and, as it were, fortuitous
500Causes. And however, I dare
501not suppress so strange an Observation,
502and therefore shall relate that
503which I had the luck to make of an
504odd sort of Electrical Attraction (as
505it seem'd,) not taken notice of (that
506I know of) by any either Naturalist
507or other Writer, and it is this.
508

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509

EXPER. VI.

510
511    That false Locks (as they call
512them) of some Hair, being
513by curling or otherwise brought to
514a certain degree of driness, or of
515stiffness, will be attracted by the
516flesh of some persons, or seem to
517apply themselves to it, as Hair is
518wont to do to Amber or Jet excited
519by rubbing. Of this I had a
520Proof in such Locks worn by two
521very Fair Ladies that you know.
522For at some times I observed, that
523they could not keep their Locks
524from flying to their Cheeks, and
525(though neither of them made any
526use, or had any need of Painting)
527from sticking there. When one of
528these Beauties first shew'd me this
529Experiment, I turn'd it into a Complemental
530Raillery, as suspecting
531there might be some trick in it,
532though I after saw the same thing
533happen to the others Locks too. But
534as she is no ordinary Virtuosa , she very

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535ingeniously remov'd my suspicions,
536and (as I requested) gave me leave to
537satisfie my self further, by desiring her
538to hold her warm hand at a convenient
539distance from one of those Locks
540taken off and held in the air. For as
541soon as she did this, the lower end
542of the Lock, which was free, applied
543it self presently to her hand:
544which seem'd the more strange, because
545so great a multitude of Hair
546would not have been easily attracted
547by an ordinary Electrical Body,
548that had not been considerably
549large, or extraordinarily vigorous.
550This repeated Observation put me
551upon inquiring among some other
552young Ladies, whether they had observed
553any such like thing, but I found
554little satisfaction to my Question, except
555from one of them eminent for
556being ingenious, who told me, that
557sometimes she had met with these
558troublesome Locks; but that all she
559could tell me of the Circumstances,
560which I would have been inform'd
561about, was, that they seem'd to her

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562to flye most to her Cheeks when
563they had been put into a somewhat
564stiff Curle, and when the Weather
565was frosty.
566
567    Some years after the making the Experiments
568about the Production of Electricity ,
569having a desire to try, whether in the
570Attractions made by Amber, the motions
571excited by the air had a considerable Interest,
572or whether the Effect were not due
573rather to the Emission and Retraction of
574Effluvia, which being of a viscous nature
575may consist of Particles either branch'd or
576hookt, or otherwise fit for some kind of
577Cohesion, and capable of being stretch'd,
578and of shrinking again, as Leather Thongs
579are: To examine this, I say, I thought
580the fittest way, if 'twere practicable,
581would be, to try, whether Amber would
582draw a light Body in a Glass whence the
583air was pumpt out. And though the Trial
584of this seem'd very difficult to make,
585and we were somewhat discouraged by
586our first attempt, wherein the weight
587of the ambient air broke our Receiver,
588which chanced to prove too weak, when
589the internal air had been with extraordinary
590diligence pumpt out; yet having a
591vigorous piece of Amber, which I had
592caus'd to be purposely turn'd and polish'd

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593for Electrical Experiments, I afterwards
594repeated the Trial, and found, that in
595warm Weather it would retain a manifest
596power of attracting for several minutes
597(for it stirred a pois'd Needle after above
5981/4 of an hour) after we had done rubbing
599it. Upon which encouragement we suspended
600it, being first well chafed, in a
601Glass Receiver that was not great, just over
602a light Body; and making haste with our
603Air-Pump to exhaust the Glass, when the
604Air was withdrawn, we did by a Contrivance
605let down the suspended Amber till it
606came very near the Straw or Feather, and
607perceived, as we expected, that in some
608Trials, upon the least Contact it would lift
609it up; and in others, for we repeated the
610Experiment, the Amber would raise it
611without touching it, that is, would attract
612it.
613
614    You will probably be the less
615dispos'd to believe, That Electrical
616Attractions must proceed from the
617Substantial Forms of the Attrahents,
618or from the Predominacy of this or
619that Chymical Principle in them, if I
620acquaint you with some odd Trials
621wherein the Attraction of light Bodies

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622seem'd to depend upon very
623small circumstances. And though
624forbearing at present, to offer you
625my thoughts about the cause of these
626surprising Phaenomena , I propose it
627onely as a Probleme to your self and
628your curious Friends, yet the main
629circumstances seeming to be of a Mechanical
630Nature, the recital of my
631Trials will not be impertinent to the
632Design and Subject of this Paper.
633
634

EXPER. VII.

635
636    I Took then a large and vigorous
637piece of Amber conveniently shaped
638for my purpose, and a downy
639feather, such as grows upon the Bodies,
640not Wings or Tails of a somewhat
641large Chicken: Then having
642moderately excited the Electrick, I
643held the Amber so near it, that the
644neighbouring part of the feather was
645drawn by it and stuck fast to it; but
646the remoter parts continued in their
647former posture. This done, I applyed
648my fore-finger to these erected

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649downy feathers, and immediately, as
650I expected, they left their preceeding
651posture, and applied themselves to it
652as if it had been an Electrical Body.
653And whether I offered to them my
654nail, or the pulpy part of my finger,
655or held my finger towards the right
656hand or the left, or directly over, these
657downy feathers that were near the
658little Quill did nimbly, and, for ought
659appear'd, equally turn themselves towards
660it, and fasten themselves to it.
661And to shew that the steams that issued
662out of so warm a Body as my
663finger were not necessary to attract
664(as men speak) the abovementioned
665feathers, instead of my finger, I applied
666to them, after the same manner,
667a little Cylindrical Instrument of Silver,
668to which they bowed and fastened
669themselves as they had done
670to my finger, though the tip of this
671Instrument were presented to them
672in several postures. The like success
673I had with the end of an Iron Key,
674and the like also with a cold piece of
675polish'd black Marble; and sometimes

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676the feathers did so readily and strongly
677fasten themselves to these extraneous
678and unexcited Bodies, that I
679have been able (though not easily)
680to make one of them draw the feather
681from the Amber it self.
682    But it is diligently to be observ'd,
683that this unusual attraction happened
684onely whilst the electrical operation
685of the excited Amber continued
686strong enough to sustain the feathers.
687For afterwards, neither the approach
688of my finger, nor that of the other
689bodies, would make the downy feathers
690change their posture. Yet as
691soon as ever the Amber was by a
692light affriction excited again, the feather
693would be disposed to apply it
694self again to the abovementioned
695Bodies.
696    And lest there should be any peculiarity
697in that particular feather, I
698made the Trials with others (provided
699they were not long enough to
700exceed the sphere of activity of the
701Amber) and found the Experiment
702to answer my expectation.

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703    I made the Experiment also at differing
704times, and with some months,
705if not rather years, of interval, but
706with the like success.
707    And lest you should think these
708Phaenomena proceed from some peculiarity
709in the piece of Amber I employed,
710I shall add, that I found uniformity
711enough in the success, when,
712in the place of Amber, I substituted
713another Electrick, and particularly a
714smooth mass of melted Brimstone.
715    These are the Phaenomena I thought
716fit to mention at present of this unusual
717way of drawing light bodies, and
718with this Experiment I should conclude
719my Notes about Electricity, but
720that I think it will not be amiss before
721I take leave of this Subject, to give
722this Advertisement, That the event
723of Electrical Experiments is not always
724so certain as that of many others,
725being sometimes much varied by
726seemingly slight circumstances, and
727now and then by some that are altogether
728over-look'd. This Observation
729may receive credit from some of

page 35

730the particulars above recited (especially concerning
731the interest of the weather, &c. in
732Electrical Phaenomena .) But now I shall add,
733that, not onely there may happen some variations
734in the success of Trials made with
735Electrical Bodies, but that it is not so
736certain as many think, whether some particular
737Bodies be or be not Electrical. For
738the inquisitive Kircherus reckons Crystall
739among those Gems to whom Nature has
740denyed the attractive power we are speaking
741of; and yet I remember not, that, among
742all the trials I have made with native
743Crystall, I have found any that was
744destitute of the power he refuses them.
745Also a late most learned Writer reciting
746the Electricks, reckon'd up by our industrious
747Countryman Gilbert , and increasing
748their number by some observed by himself,
749(to which I shall now add, besides
750white Saphyrs, and white English Amethysts,
751the almost Diaphanous spar of Lead
752Ore) denies Electricity to a couple of transparent
753Gems, the Cornelion and the Emrald.
754And I do the less wonder he should
755do so to the former, because I have my self
756in vain tried to make any attraction with
757a piece of Cornelion so large and fair, that
758'twas kept for a rarity; and yet with divers
759other fine Cornelions I have been able
760to attract some light bodies very manifestly,

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761if not briskly; and I usually wear a
762Cornelian Ring, that is richly enough endowed
763with Electricity. But as for Emralds,
764as I thought it strange that Nature
765should have denied them a Quality she
766has granted to so many other Diaphanous
767Gems, and even to Crystal, so I thought
768the assertion deserved an Examen , upon
769which I concluded, that at least it does
770not universally and constantly hold true.
771I had indeed seen in a Ring a Stone of
772price and great lustre, which, though
773green, I found to be, (as I guess'd it would
774prove) vigorously enough Electrical. But
775this Experiment, though seemingly conclusive,
776I did not look upon as a fair trial,
777because the Stone was not a true Emrald,
778but, which is rare, a green Saphir. And
779I learned by inquiry of the skillful Jeweller
780that cut it, that it was so far from having
781the softness of an Emrald, that he
782found it harder than blew Saphyrs themselves,
783which yet are Gems of great hardness,
784and by some reputed second to none,
785but Diamonds. Without therefore concluding
786any thing from this Experiment,
787save that, if the assertion I was to examin
788were true, the want of an Electrical faculty
789might be thought a Concomitant rather
790of the peculiar Texture of the Emrald
791than of its green colour, I proceeded

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792to make trial with three or four Emralds,
793whose being true was not doubted, and
794found them all somewhat, though not equally,
795endow'd with Electricity, which I
796found to be yet more considerable in an
797Emrald of my own, whose colour was so
798excellent, that by skilful persons 'twas
799look'd on as a rarity. And though, by this
800success of my inquiry, I perceived I could
801not, as else I might have done, shew the
802Curious a new way of judging of true and
803false Emralds, yet the like way may be,
804though not always certain, yet oftentimes
805of use, in the estimating whether Diamonds
806be true of counterfeit, especially,
807if, being set in Rings, the surest way of
808trying them cannot conveniently be employed.
809For whereas Glass, though it
810have some Electricity, seems, as far as I
811have observed, to have but a faint one,
812there are often found Diamonds that have
813a very vigorous one. And I do not remember
814I met with any Electrick of the
815same bulk, that was more vigorous than
816a rough Diamond I have, which is the
817same that I formerly mentioned to have
818moved a Needle above three minutes after
819I had ceased to chafe it. And this
820brings to my mind, that it has been observed,
821that Diamonds draw better whilst
822rough, than they do after they are cut and

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823polish'd; which seeming to contradict
824what has been observed by others and by
825us also, that Amber, for instance, attracts
826more vigorously if the surface be made very
827smooth than otherwise, it induces me
828to conjecture, that, if this Observation about
829Diamonds be true, as some of my
830trials have now and then inclined me to
831think it, and if it do not in some cases
832considerably depend upon the loss of the
833(Electrical) Substance of the Stone, by its
834being cut and ground, the Reason may
835possibly be, that the great rapidness with
836which the Wheels that serve to cut and
837polish Diamonds must be mov'd, does excite
838a great degree of heat, (which the
839senses may easily discover) in the Stone,
840and by that and the strong concussion it
841makes of its parts, may force it to spend
842its effluviable matter, if I may so call it,
843so plentifully, that the Stone may be impoverish'd
844and perhaps also, on the account
845of some little change in its Texture,
846be rendred lesse disposed to emit those
847effluvia that are Instruments of Electrical
848Attraction. But as I willingly leave the
849matter of Fact to further Trial, so I do
850the Cause of it, in case it prove true, to
851farther Inquiry.
852
853    Finis.